A Broadband Frequency Selective Rasorber with Switchable Absorption and Transmission Characteristics

This paper proposes a dual-polarized switchable frequency selective rasorber (FSR) composed of a passive lossy layer, an active lossy layer, and an active frequency selective surface (FSS). By controlling the bias states of the diodes in the active lossy layer and the active FSS, the FSR can operate in two distinct modes: low-frequency absorption with high-frequency transmission, and broadband absorption across the entire band. In the low-absorption/high-transmission mode, the absorber exhibits over 90% absorptivity from 3 to 7.5 GHz and transmission from 9 to 11 GHz with an insertion loss less than 1 dB. In the full-band stealth mode, the absorption remains above 90% across a broad frequency range from 2.9 to 14.8 GHz. To enhance practical applicability, the lossy and frequency selective layers adopt parallel-fed and series-fed configurations, respectively. Benefiting from a novel transmission-enhancing structure embedded within the lossy layer, the proposed FSR significantly improves the insertion loss and bandwidth of the passband without compromising its absorption performance. Furthermore, the design demonstrates strong angular stability under oblique electromagnetic incidence.